This invention relates to an adjustable compass for mechanically drawing varying ellipses of predetermined dimensions.
An ellipse is a geometric figure defined as a closed curve produced when a cone is cut, intermediate its apex and base, by a plane inclined obliquely to the cone's axis. Characteristic of such a figure is that it has perpendicularly intersecting chords of maximum and minimum lengths commonly known as the major axis and minor axis of the ellipse, respectively.
Numerous instances occur, such as in connection with the preparation of engineering and architectural drawings, wherein it is desired and necessary to depict ellipses figuratively and accurately. When a series of ellipses desired to be drawn are identical, a template drawing guide reflecting the dimensions of the common ellipse may be utilized. This approach, however, requires a series of templates for every conceivable ellipse, and thus is not feasible. The more commonly employed practice is to utilize a drafting guide referred to as a "french curve". This latter approach, however, while workable, is not totally acceptable in being time consuming, costly, and inherently not totally accurate. Hence, a search has long existed in the art for an inexpensive, versatile instrument adapted to rapidly and accurately draw varying ellipses.